Immune - stem cell cross-talk in the central nervous system: How oligodendrocyte progenitor cells interact with immune cells.

The interaction between immune and stem cells has proven essential for homeostasis and regeneration in a wide range of tissues. However, since the central nervous system was long considered an immune-privileged organ, its immune-stem cell axis was not deeply investigated until recently. Research has shown that oligodendrocyte progenitor cells, a highly abundant population of adult brain stem cells, establish bidirectional interactions with the immune system. Here, we provide an overview of the interactions that oligodendrocyte progenitor cells have with tissue-resident and recruited immune cells, paying particular attention to the role they play in myelin regeneration and neuroinflammation. We highlight the described role of oligodendrocyte progenitor cells as key active players in neuroinflammation, overriding the previous concept that oligodendrocyte progenitor cells are mere recipients of immune signals. Understanding the mechanisms behind this bidirectional interaction holds great potential for the development of novel therapeutic approaches limiting neuroinflammation and promoting myelin repair. A better understanding of the central nervous system's immune-stem cell axis will also be key for tackling two important features shared across neurodegenerative diseases, neuroinflammation and myelin loss.